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The widely observed negative scaling relationship between organism size and abundance is predicted to have a universal −0.75 scaling exponent across all life forms. However, factors influencing frequently observed deviations from this exponent, such as ecosystem succession and organism traits, remain poorly understood.We explore the dependence of size–density scaling on ecosystem succession and organism traits by analysing size–density relationships in trees and soil invertebrates across 183 temperate forest plots comprising urban secondary forests, urban old‐growth forests and non‐urban natural forests.Exponents of scaling relationships in urban tree and invertebrate communities progressively steepened with increasing restored (planted) forest stand age as small organisms increased in abundance. In contrast, non‐urban tree scaling relationships flattened during succession with exponents veering away from −0.75, whereas urban tree and invertebrate communities converged towards this prediction in later successional stages.Our results shed light on how the body size structure of tree and soil invertebrate communities spanning multiple trophic levels shift over successional time as the relative abundances of large versus small‐bodied organisms increase. This study emphasises the fundamental influence of organismal traits and ecosystem succession on scaling relationships of organism body size and abundance. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

A foundational concept in ecology is the positive relationship between habitat heterogeneity and species diversity. Epiphytes demonstrate microhabitat specialization to particular areas within a tree; thus, epiphyte communities are potentially influenced by the structural heterogeneity of host trees. We evaluated the relationship between structural features of Acer macrophyllum and epiphyte distributions and abundance in a temperate rainforest in Washington, USA. Epiphytes and structural features of three Acer macrophyllum trees were systematically surveyed using the point-intercept method from the base to the crown and on three branches for each tree. Rarefied species richness increased with structural richness. Species richness along the trunk differed significantly among types of structural features (i.e., broken branches, burls, holes, rivets, branches, and trunks); broken branches had the highest species richness and branches had the lowest, followed by trunks. Rarefied species richness increased with height and peaked at 12 m, but the relationship between structural diversity and height was not significant. The species that occurred on branches were different to those that occurred on trunks, and species composition varied significantly among trunk features. The high structural diversity in northern temperate rainforest trees influenced the fine-scale distribution of nonvascular epiphytes and may explain their coexistence in tree crowns. [ABSTRACT FROM AUTHOR]

Context: Evidence for declines in insect populations is growing with climate change being one suspected driver. Forests, however, are still underrepresented in the relevant research. Recent droughts (2018–2020) have severely affected forests in Central Europe and have been linked to declines in carabid abundance, biomass as well as changes in species traits at the local scale. Objective: We tested drought effects on forest carabids at regional scale. We additionally investigated whether variability in drought effects could be explained with the initial community composition and the local environmental context. Methods: We used generalized linear mixed models to compare data from 1999 to 2001 and 2020 to 2022 across eleven old beech forest sites of high conservation interest in North-East Germany and investigated changes in carabid abundance, biomass, Hill numbers and selected species traits. We then tested additional community-related and environmental predictors to explain spatial variability in changes in biomass. Results: We found significant declines in biomass of 65% and in abundance of 51%. There were no significant changes in Hill numbers. We found consistent evidence that declines affected especially larger and less mobile species. Declines and changes in species traits also occurred in strictly protected old-growth beech forests. Among environmental predictors, landscape composition explained local variability in biomass declines best with stronger decline at forest sites with less forest area in their vicinity. Conclusions: Our findings reveal large-scale declines in forest carabids in the context of recent droughts and highlight the exceptional role of landscape composition in this regard. Future insect conservation strategies need to incorporate the landscape context and potential exposure to extreme weather. [ABSTRACT FROM AUTHOR]

This editorial highlights the significance of old-growth forests in southeast Europe for forest management. The authors stress the importance of studying these forests, which have developed naturally without human intervention, to gain knowledge that can be applied to commercial forests. The authors also emphasize the threats to forest ecosystems, such as climate change and invasive pests, and the need to protect and preserve old-growth forests. They discuss the differences between old-growth forests and commercial forests in terms of structural diversity and biodiversity. The editorial concludes by underscoring the ecological and socioeconomic importance of old-growth forests in southeast Europe and the need for further research in this field. [Extracted from the article]

Nematode communities in natural pristine forests composed of trees aged over 1000 years have not been thoroughly studied. Old-growth forests can provide diverse microhabitats for nematodes such as fallen trees with mossy conditions. This study aimed to characterize the community and trophic compositions of nematodes in relation to different microhabitats in old-growth Japanese cedar (Cryptomeria japonica (L. f.) D. Don) forests in Yakushima Island, Japan. To this aim, nematodes retrieved from four different types of microhabitats were morphologically identified at the family/genus level and divided into five trophic groups. A nonmetric multidimensional scaling scatterplot showed that nematode communities clustered significantly in each microhabitat and their community compositions were significantly affected by C/N ratio. With respect to nematode trophic composition, bacterivorous nematodes dominated decaying barks of fallen trees, with a relative abundance of 45%, while fungivorous nematodes were dominant in living barks of cedar trunks (61%). Predatory–omnivorous nematodes predominated in mosses of fallen trees (51%). These results showed that nematode community and trophic composition were different among microhabitats characterized by nutrient conditions. The predatory–omnivorous nematodes were abundant in mosses with N-rich conditions. In contrast, fungivorous nematodes were abundant in cedar trunks with high C/N conditions. Thus, old-growth natural forests can provide diverse microhabitats where various nematode taxa coexist due to the presence of fallen trees and mosses. [ABSTRACT FROM AUTHOR]

The paper investigates the natural regeneration of downed deadwood in the Janj primeval forest. The old-growth forest is located in the southwestern part of the Republic of Srpska, which is dominated by dolomite geological base on which cambial soils were formed. The climate is perhumid and mountainous and the plantation belongs to the Piceo-Abieti-Fagetum community. The hectare contains 517 live trees with a total basal area of 53.0 m2/ha and a volume of 876 m3/ha. Twenty six downed deadwoods classified into three different degrees of decay were included in the study, where fir and spruce seedlings were found to be predominant and beech seedlings were rarely represented. The first degree of decay includes 7 (26.9 %), the second 8 (30.7 %), and the third 11 (42.3 %). The total volume of deadwood is 110.82 m3/ha with an average volume per tree of 4.2 m3/ha. The total number of seedlings on fallen dead trees is 836 seedlings (Abies alba – 89.59 %, Picea abies – 10.17 %, Fagus silvatica – 0.24 %). Fir seedlings are found on 25 fallen trees, spruce on 18 fallen trees, and beech on 2 fallen trees. Regarding quality, on average fir seedlings are better than spruce seedlings, but both species show a lot of senescence and very small size of current height increment. Most seedlings belong to the third quality class (fir – 46.2 %, spruce – 61.1 %), followed by second class (fir – 34.6 %, spruce – 22.2 %) and third class (fir – 19.2 %, spruce – 16.7 %). The total number of seedlings was found to have a statistically significant difference in the amount of downed deadwood depending on the degree of decay, and the number of seedlings depended on the degree of tree decay. The number of seedlings increased with increasing volume and length of rotten trees. Acknowledgеments: This article is the result of the project “Аdaptive management of Natural Resource of the Republic of Srpska”. We would like to thank the Ministry of Scientific and Technological Development, Higher Education and Information Society of the Republic of Srpska for their support in the realization of the project. For citation: Govedar Z., Prokhorova N., Babić V., Dukić V., Kanjevac B., Bilić S. Natural Regeneration on Deadwood in the Primeval Forest Janj. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 90–102. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-90-102

A foundational concept in ecology is the positive relationship between habitat heterogeneity and species diversity. Epiphytes demonstrate microhabitat specialization to particular areas within a tree; thus, epiphyte communities are potentially influenced by the structural heterogeneity of host trees. We evaluated the relationship between structural features of Acer macrophyllum and epiphyte distributions and abundance in a temperate rainforest in Washington, USA. Epiphytes and structural features of three Acer macrophyllum trees were systematically surveyed using the point-intercept method from the base to the crown and on three branches for each tree. Rarefied species richness increased with structural richness. Species richness along the trunk differed significantly among types of structural features (i.e., broken branches, burls, holes, rivets, branches, and trunks); broken branches had the highest species richness and branches had the lowest, followed by trunks. Rarefied species richness increased with height and peaked at 12 m, but the relationship between structural diversity and height was not significant. The species that occurred on branches were different to those that occurred on trunks, and species composition varied significantly among trunk features. The high structural diversity in northern temperate rainforest trees influenced the fine-scale distribution of nonvascular epiphytes and may explain their coexistence in tree crowns.

In light of the problem of maintaining the resilience of terrestrial ecosystems in the face of a changing climate, it is especially important to understand the mechanisms for maintaining biodiversity in intact forests that have not been harvested. The aim of this study is the synthesis of comprehensive long-term studies of the structural–functional diversity and dynamics of the Vepssky Forest, a primeval middle taiga woodland. The objectives include an analysis of (1) the natural disturbances regime; (2) the proportion of biogeocenoses (BGC) with various dynamics types associated with different site conditions, as well as windfall gaps; (3) the age structure of the forest massif; (4) the species composition dynamics, growing stock, number of trees, coarse woody debris (CWD), as well as natural regeneration and mortality of forest stands within the forest massif, on the levels of the whole massif and in different BGC types; and (5) the factors that determine the spatiotemporal organization the studied forest massif. Fulfilling these objectives is possible only within the framework of an integrated approach. We used data from aerial photography, inventories on transects, route surveys, mapping of the forest composition and age structure, and sites conditions and soils, as well as regularly established permanent circular sample plots of a fixed radius. The frequency and intensity of winds determines the structural diversity and dynamics of the studied forest massif. In turn, the diversity of the forest massif determines the severity of wind disturbances, as well as the patterns and rate of post-disturbance successional changes. Spruce forests prevailing in well-drained sites are subject to windthrows of medium and high severity—19% of their total area are windfall gaps. The most part of them (43%) has a relatively uneven age structure with a predominance of the 161–200 year old trees. The forest stands, which have an all-aged structure (15%), are confined to poorly drained sites. Mean growing of the forest massif has decreased by 15% (from 321 to 274 m3 ha-1) from 1991 to 2019 as a result of windthrows. The volume of CWD, represented mainly by fallen and leaning logs, averaged 71% of the volume of living trees. Its variations reflected the phases of forest stand dynamics due to wind induced disturbances. The number of BGC in the stabilization phase has decreased, while the proportion of BGC in the digression and growing stock increase phases of dynamics has increased. The "top story" mortality prevails; i.e., mainly larger trees die off. The mean annual mortality at the time of the last inventory was 3.5% of the total growing stock. The spruce share in the forest stands remains quite stable. The results of many years of research in the Vepssky Forest have many practical implications, including the development of optimal scenarios for forest management, as well as for the conservation and/or restoration of biodiversity in managed forests. [ABSTRACT FROM AUTHOR]

The forestry continuity and the occurrence of red-listed lichens are critical criteria needed for the designation of protected areas. This study highlights the occurrence in time of red-listed lichen species within the Comana Natural Park. 31 lichens were identified within the study area, of which one is designated as national red-listed lichen such as Ramalina obtusata and the other one is designated as global red-listed lichen by IUCN, for instant Flavoparmelia caperata. An important aspect is represented by the occurrence of F. caperata on old oaks both in the Padina Tătarului Peony Reserve and in the Oloaga-Grădinari Butcher's broom Reserve. The forest habitats of the Comana Natural Park are mainly represented by old-growth forests and therefore is important to reduce the anthropogenic impact on these habitats needed for the long-term conservation of lichen species. [ABSTRACT FROM AUTHOR]

The Special Issue "Impact of climate warming and disturbances on forest ecosystems" underscores the critical importance of understanding how forests respond to these environmental challenges and the legacy of past management practices. Forest ecosystems are facing significant challenges due to ongoing climate change, characterized by rising temperatures and increased frequency of extreme events. The rapid pace of climate change is altering disturbance patterns and the adaptability of forests, which have a direct impact on ecosystem services that contribute to human well-being. This Special Issue features 11 research papers from nine countries. Some key outputs from these research papers include evidence on how climate change is already impacting forest ecosystems. For instance, the climatic envelope of many forest species has shifted due to global warming, making species more vulnerable, especially in lower elevations and at the edges of their distribution. Urgent adaptive measures in forest management are necessary to address this challenge. Climate change also affects vegetation phenology, tree growth, stand productivity, reproduction rates, and stand regeneration. Remote sensing data and ecological modeling techniques play a crucial role in monitoring and understanding these changes, especially in remote regions where field measurements are limited. The rising frequency and intensity of extreme events like droughts, windstorms, and forest fires require enhanced prediction and automatic monitoring. Leveraging machine learning tools and remote sensing data is imperative. This Special Issue provides insights into the intricate relationships among forests, climate change, and human interventions. We provide further research recommendations for the quantification and automated monitoring of forest fires and the management of forests to better withstand storms and increase their resilience to climate change. [ABSTRACT FROM AUTHOR]

In this era of biodiversity loss and climate change, quantifying the impacts of natural disturbance on forest communities is imperative to improve biodiversity conservation efforts. Epiphytic and epixylic lichens are effective forest quality bioindicators, as they are generally long-lived organisms supported by continuity of specific forest structures and their associated microclimatic features. However, how lichen communities respond to the effects of fluctuating historical disturbances remains unclear. Using a dendrochronological approach, this study investigates how natural disturbance dynamics indirectly influence various lichen community metrics in some of Europe's best-preserved primary mixed-beech forests. Mixed modelling revealed that natural historical disturbance processes have decades-long effects on forest structural attributes, which had both congruent and divergent impacts on lichen community richness and composition. Total species richness indirectly benefited from both historical and recent higher-severity disturbances via increased standing dead tree basal area and canopy openness respectively - likely through the presence of both pioneer and late-successional species associated with these conditions. Red-listed species richness showed a dependence on habitat continuity (old trees), and increased with disturbance-related structures (standing dead trees) whilst simultaneously benefiting from periods without severe disturbance events (old trees and reduced deadwood volume). However, if the disturbance occurred over a century in the past, no substantial effect on forest structure was detected. Therefore, while disturbance-mediated forest structures can promote overall richness, threatened species appear vulnerable to more severe disturbance events – a concern, as disturbances are predicted to intensify with climate change. Additionally, the high number of threatened species found reinforce the critical role of primary forest structural attributes for biodiversity maintenance. Hence, we recommend a landscape-scale conservation approach encompassing forest patches in different successional stages to support diverse lichen communities, and the consideration of long-term disturbance dynamics in forest conservation efforts, as they provide critical insights for safeguarding biodiversity in our changing world.

A unique crustose lichen species was recently documented from various types of preserved forests across boreal and temperate Europe (Norway, Ukraine, the Czech Republic) and the Caucasus (Russia). It is formally described here as the new species Biatora amylacea. A phylogeny based on ITS and mtSSU sequences demonstrates that it belongs to an isolated group within the core of Biatora s. lat., together with the recently described B. radicicola. It is a distinctive taxon within the genus on account of its amyloid exciple, otherwise known only from members of the Biatora rufidula group. The new species is also characterized by amyloid thalline hyphae and the production of soredia with a blue-green pigment. This microlichen may serve as a bioindicator species of old-growth forests. [ABSTRACT FROM AUTHOR]

Old-growth forests have a primary environmental and ecological value, as they closely recall primeval forests and the natural forest landscape that was spread throughout Italy and Europe before man intervention heavily altered the functioning of most natural ecosystems. These ecosystems are more and more recognized as keystones of environmental policies (i.e., the EU Biodiversity Strategy 2030) aimed to preserve biodiversity and mitigate the impacts of climate change. A recent report highlights that Europe's old-growth forests account for only 3 percent of the overall forest surface. The majority of italian old-growth forests are located along the Apennines, especially in the Pollino, Sila and Aspromonte National Parks, in remote montane areas characterized by irregular topographical conditions (i.e., high slopes and/or shallow soils) which hamper the access and exploitation of these less productive stands, thus allowing the survival of old-growth forests for many centuries. The ongoing climate change is a significant challenge to the conservation of old-growth forests, particularly in areas such as the Mediterranean basin, where an intensification of extreme climate events is expected. Heat waves can exacerbate drought's negative impacts on tree growth and survival, leading to reduced woody carbon stocks and biodiversity in old-growth forests. To date, there is poor understanding of such highly valuable and extremely fragile natural ecosystems in Italy. Insights are available based on data gathered as part of two research programs, funded by the Italian Ministry of the Environment and Land and Sea Protection, with the purpose of creating a Network of Old Growth Forests in Italy's National Parks. In this study, we aimed to highlight the role and importance of old-growth forests, focusing on those located within the Pollino National Park. A comprehensive overview of the key strengths and weaknesses, that mark these peculiar forest ecosystems, was followed by a discussion of the future outlook, grounded on strategies that will ensure not only the protection and conservation of these ecosystems, but also their development and promotion. [ABSTRACT FROM AUTHOR]

The Tongass National Forest in southeast Alaska, USA, includes the Alexander Archipelago and narrow North American mainland, comprising one of the largest remaining, largely pristine, coastal temperate rainforest in the world. Management of the Tongass has become increasingly challenging because of expectations of a conservation framework designed to maintain viable populations of native wildlife species while decades of extensive clearcut logging of old‐growth forests has continued. We used the findings of multiple published studies conducted on the Tongass from 1998 to 2017 to examine 4 assumptions of its wildlife conservation strategy (WCS): forest planning assessments of wildlife viability were realistic, forest management and conservation policies are implemented at appropriate ecological scales, old‐growth reserves are effective habitat conservation areas and ensure functional connectivity, and forest‐wide standards and guidelines ensure sufficient habitat for sensitive species in managed landscapes. Several ecological field studies, population and spatial analyses and modeling, and statistical analyses revealed that wildlife viability assessments to evaluate forest plan alternatives underestimated the risk of extinction by only examining individual vulnerable species rather than considering joint probabilities across multiple species; the ecological scale of management and conservation policies do not adequately consider area‐sensitive vulnerabilities of island communities as evidenced by the increasing risk of extirpation of island endemics whose populations have become isolated and reduced; old‐growth reserves are unlikely to maintain viable populations of endemic small mammals in isolation or as functionally connected metapopulations; and a spatially explicit analysis of individual home ranges demonstrated that forest‐wide standards and guidelines provide about half the breeding habitat needed by a federally listed endemic raptor, the Queen Charlotte goshawk (Accipiter gentilis laingi), of which only half of that is secure. Thus, assertions that the WCS is properly functioning as designed are dubious because a comprehensive monitoring plan has not been implemented and vital underlying assumptions are not supported by available science. We recommend 3 forest management and conservation policy adjustments: limit size and location old‐growth forest harvests, restore forests through intermediate stand management of second growth, and conduct a formal review of WCS elements and assumptions. [ABSTRACT FROM AUTHOR]

The study aimed to quantify annual mortality and recruitment rates on permanent research plots in the Badínsky prales old-growth forest. The data measured in four stands originate from six censuses, which together cover a 48-year period. The mean annual mortality rate reached 4.2% (DBH > 2 cm) or 2.3% (DBH > 8 cm). The mortality peaked in the first part of the observation period, probably indicating an intermediate disturbance activity, and the subsequent declining trend led to minimum annual mortality during the last 20 years. We found substantially higher fir mortality in comparison with beech, primarily during the first decades of the measurement period. Among three size categories, the stems with DBH 2-8 cm showed the highest mortality rate. We detected the minimum fir recruitment rate throughout the observation period; on the other hand, the beech recruitment rate was relatively high responding to the open canopy. Standing and lying deadwood volumes indicated similar trends like mortality did, and high values of fir standing deadwood observed during the first decades can signify that a relatively high proportion of mortality was related to the fir decline caused by air pollution.

Old-growth forests have a primary environmental and ecological value, as they closely recall primeval forests and the natural forest landscape that was spread throughout Italy and Europe before man intervention heavily altered the functioning of most natural ecosystems. These ecosystems are more and more recognized as keystones of environmental policies (i.e., the EU Biodiversity Strategy 2030) aimed to preserve biodiversity and mitigate the impacts of climate change. A recent report highlights that Europe’s old-growth forests account for only 3 percent of the overall forest surface. The majority of italian old-growth forests are located along the Apennines, especially in the Pollino, Sila and Aspromonte National Parks, in remote montane areas characterized by irregular topographical conditions (i.e., high slopes and/or shallow soils) which hamper the access and exploitation of these less productive stands, thus allowing the survival of old-growth forests for many centuries. The ongoing climate change is a significant challenge to the conservation of old-growth forests, particularly in areas such as the Mediterranean basin, where an intensification of extreme climate events is expected. Heat waves can exacerbate drought’s negative impacts on tree growth and survival, leading to reduced woody carbon stocks and biodiversity in old-growth forests. To date, there is poor understanding of such highly valuable and extremely fragile natural ecosystems in Italy. Insights are available based on data gathered as part of two research programs, funded by the Italian Ministry of the Environment and Land and Sea Protection, with the purpose of creating a Network of Old Growth Forests in Italy’s National Parks. In this study, we aimed to highlight the role and importance of old-growth forests, focusing on those located within the Pollino National Park. A comprehensive overview of the key strengths and weaknesses, that mark these peculiar forest ecosystems, was followed by a discussion of the future outlook, grounded on strategies that will ensure not only the protection and conservation of these ecosystems, but also their development and promotion.

Forests are major carbon sinks, but tree species composition and forest biomass have changed significantly under climate change. However, the extent to which forests have changed with climate change is unclear due to a lack of information before the recent climate change. In this study, we used forest inventory and environmental data (480 plots, 467 ha in total) from 1929 to 1938 in northern mixed forests in Japan (1) to estimate the biomass of the forest at that time, (2) to determine the environmental factors (temperature, precipitation, topographic wetness index, solar radiation, geology) affecting the AGB and species-specific biomass and (3) to estimate the relationship between AGB and diversity, structural equation models were used to determine whether the relationships are significant. The results showed that the average AGB of the forest was 61±22.4 (MgC/ha), which was not much higher than that of the present forest after human disturbances. Regarding species-specific biomass, biomass for subboreal conifers tended to increase in areas with less precipitation, and biomass for cool temperate deciduous broadleaved trees tended to increase in areas with more precipitation. Environmental factors indirectly affected AGB via forest structural factors, and the relationship between diversity and AGB was insignificant. This study revealed the feature of the forest ecosystem before recent climate change, and showed the potential for a detailed understanding of the effects of environmental factors related to biomass by analyzing species-specific response.

The EU Biodiversity Strategy 2030 (EUBDS) aims to preserve and restore biodiversity by protecting large areas in the EU. An extensive part of these protected areas will presumably be covered by forests. This study analyses the economic effects of EUBDS implementation on German forestry in two scenarios, based on different possible interpretations of the EUBDS' key commitments, using a forest economic simulation model. A special focus is placed on the opportunity costs of coarse wood debris (CWD). Over a simulated 200-year period, a decrease in timber harvest of 13% and 44% is estimated under the respective scenario assumptions. This leads to a reduction in the silvicultural contribution margin (SCM) of on average 0.25 B EUR a−1 (14%) and 0.79 B EUR a−1 (45%). In terms of the total SCM, protected forests contribute 35% and 15% in the two scenarios. The accumulation and preservation of CWD incurs a substantial loss of utility, as 15% and 19% of annual logging is required for conservation purposes. However, the EUBDS may also provide economically tangible benefits. A rational decision would be to implement a scenario if the "net benefit" from the protected status exceeds the losses from set-aside and conservation requirements. [ABSTRACT FROM AUTHOR]

It is desirable to update scientific knowledge on key aspects of forest biodiversity protection and implement it more effectively into forestry practice. A review was prepared across the Web of Science Core Collection database, searching in the “Topic” section, using a key words string: ((biodiversity OR „biological diversity“) AND („forest management“ OR forestry) AND „central Europe“). Particular attention should be paid to ending the clear-cutting and monocultures cultivation, as the most significant forms of intensive management. It is necessary to focus on the restoration of a varied tree species composition with respect for succession, the protection of old-growth forest habitats and their structures, as well as the restoration of open forests and the renewal of historical management forms (e.g. coppicing and forest grazing). In the interest of biodiversity, a combination of integrative and segregative management can be highly recommended. Reserves are essential as habitats for the most endangered species, but their role must be supported and complemented by integrative management in commercial forests. Such integrative management should emulate natural disturbances regime, predominantly with mixed severity. [ABSTRACT FROM AUTHOR]

In the context of global decline in old‐growth forest, historical ecology is a valuable tool to derive insights into vegetation legacies and dynamics and develop new conservation and restoration strategies. In this cross‐disciplinary study, we integrate palynology (Lago del Pesce record), history, dendrochronology, and historical and contemporary land cover maps to assess drivers of vegetation change over the last millennium in a Mediterranean mountain forest (Pollino National Park, southern Italy) and discuss implications in conservation ecology. The study site hosts a remnant beech–fir (Fagus sylvatica–Abies alba) mixed forest, a priority habitat for biodiversity conservation in Europe. In the 10th century, the pollen record showed an open environment that was quickly colonized by silver fir when sociopolitical instabilities reduced anthropogenic pressures in mountain forests. The highest forest cover and biomass was reached between the 14th and the 17th centuries following land abandonment due to recurring plague pandemics. This rewilding process is also reflected in the recruitment history of Bosnian pine (Pinus heldreichii) in the subalpine elevation belt. Our results show that human impacts have been one of the main drivers of silver fir population contraction in the last centuries in the Mediterranean, and that the removal of direct human pressure led to ecosystem renovation. Since 1910, the Rubbio State Forest has locally protected and restored the mixed beech–fir forest. The institutions in 1972 for the Rubbio Natural Reserve and in 1993 for Pollino National Park have guaranteed the survival of the silver fir population, demonstrating the effectiveness of targeted conservation and restoration policies despite a warming climate. Monitoring silver fir populations can measure the effectiveness of conservation measures. In the last decades, the abandonment of rural environments (rewilding) along the mountains of southern Italy has reduced the pressure on ecosystems, thus boosting forest expansion. However, after four decades of natural regeneration and increasing biomass, pollen influx and forest composition are still far from the natural attributes of the medieval forest ecosystem. We conclude that long‐term forest planning encouraging limited direct human disturbance will lead toward rewilding and renovation of carbon‐rich and highly biodiverse Mediterranean old‐growth forests, which will be more resistant and resilient to future climate change. [ABSTRACT FROM AUTHOR]

The study aimed to quantify annual mortality and recruitment rates on permanent research plots in the Badínsky prales old-growth forest. The data measured in four stands originate from six censuses, which together cover a 48-year period. The mean annual mortality rate reached 4.2% (DBH > 2 cm) or 2.3% (DBH > 8 cm). The mortality peaked in the first part of the observation period, probably indicating an intermediate disturbance activity, and the subsequent declining trend led to minimum annual mortality during the last 20 years. We found substantially higher fir mortality in comparison with beech, primarily during the first decades of the measurement period. Among three size categories, the stems with DBH 2-8 cm showed the highest mortality rate. We detected the minimum fir recruitment rate throughout the observation period; on the other hand, the beech recruitment rate was relatively high responding to the open canopy. Standing and lying deadwood volumes indicated similar trends like mortality did, and high values of fir standing deadwood observed during the first decades can signify that a relatively high proportion of mortality was related to the fir decline caused by air pollution. [ABSTRACT FROM AUTHOR]

The Special Issue “Impact of climate warming and disturbances on forest ecosystems” underscores the critical importance of understanding how forests respond to these environmental challenges and the legacy of past management practices. Forest ecosystems are facing significant challenges due to ongoing climate change, characterized by rising temperatures and increased frequency of extreme events. The rapid pace of climate change is altering disturbance patterns and the adaptability of forests, which have a direct impact on ecosystem services that contribute to human well-being. This Special Issue features 11 research papers from nine countries. Some key outputs from these research papers include evidence on how climate change is already impacting forest ecosystems. For instance, the climatic envelope of many forest species has shifted due to global warming, making species more vulnerable, especially in lower elevations and at the edges of their distribution. Urgent adaptive measures in forest management are necessary to address this challenge. Climate change also affects vegetation phenology, tree growth, stand productivity, reproduction rates, and stand regeneration. Remote sensing data and ecological modeling techniques play a crucial role in monitoring and understanding these changes, especially in remote regions where field measurements are limited. The rising frequency and intensity of extreme events like droughts, windstorms, and forest fires require enhanced prediction and automatic monitoring. Leveraging machine learning tools and remote sensing data is imperative. This Special Issue provides insights into the intricate relationships among forests, climate change, and human interventions. We provide further research recommendations for the quantification and automated monitoring of forest fires and the management of forests to better withstand storms and increase their resilience to climate change.

We present a data set resulting from the first round of a national monitoring program of forest reserves. It contains 9538 permanent plots, distributed across 111 study sites in mainland France (including Corsica). Notably focusing on dead wood measurement, this protocol has primarily been applied in strict forest reserves and special nature reserves (sensu Bollmann & Braunisch 2013), with 68% (6494) of the plots being currently located in strict forest reserves (unmanaged) and 24.7% (2363 plots) in forests unmanaged for at least 50 years. Sites cover a large variety of ecological conditions, from lowland to subalpine forests, but with an underrepresentation of Mediterranean forests (Table 1). The protocol assesses all the stages of a tree's life cycle, from seedling to decomposed lying dead wood. On each plot, a combination of three sampling techniques was used: (1) fixed‐area inventory for regeneration, standing dead trees, living trees, and coarse woody debris (CWD) with diameter over 30 cm; (2) transect lines for CWD with diameter <30 cm; and (3) fixed‐angle plot method for living trees with diameter at breast height (DBH) >30 cm (using a relascopic angle of 3%). Measurements include exact tree location (azimuth, distance), species, diameter(s), tree‐related microhabitats, decay stage and bark cover, and seedling cover. With ongoing climate change, the program network can also provide important information to monitor changes in forest ecosystems. It can also be used as forest management monitoring or conservation status assessment. These data are freely available for noncommercial scientific use (Creative Commons Attribution 4.0 CC BY SA 4.0) with attribution, and this paper must be cited if this material is reused. [ABSTRACT FROM AUTHOR]

Climate change is contributing to biodiversity redistributions and species declines. However, cooler microclimate conditions provided by old‐growth forest structures compared with surrounding open or younger forests have been hypothesized to provide thermal refugia for species that are sensitive to climate warming and dampen the negative effects of warming on population trends of animals (i.e., the microclimate buffering hypothesis). In addition to thermal refugia, the compositional and structural diversity of old‐growth forest vegetation itself may provide resources to species that are less available in forests with simpler structure (i.e., the insurance hypothesis). We used 8 years of breeding bird abundance data from a forested watershed, accompanied with sub‐canopy temperature data, and ground‐ and LiDAR‐based vegetation data to test these hypotheses and identify factors influencing bird population changes from 2011 to 2018. After accounting for imperfect detection, we found that for 5 of 20 bird species analyzed, abundance trends tended to be less negative or neutral at sites with cooler microclimates, which supports the microclimate buffering hypothesis. Negative effects of warming on two species were also reduced in locations with greater forest compositional diversity supporting the insurance hypothesis. We provide the first empirical evidence that complex forest structure and vegetation diversity confer microclimatic advantages to some animal populations in the face of climate change. Conservation of old‐growth forests, or their characteristics in managed forests, could help slow the negative effects of climate warming on some breeding bird populations via microclimate buffering and possibly insurance effects. [ABSTRACT FROM AUTHOR]

Background: Suitable climate and availability of habitats for roosting, foraging, and dispersing are critical for the long-term persistence of bat species. The giant noctule (Nyctalus lasiopterus) represents one of the lesser-known European bats, especially regarding the environmental factors which shape its distribution. Methodology: We integrated climate-based ecological niche models with information about topography and rivers' network to model weighted suitability for N. lasiopterus in the western Palearctic. The weighted suitability map was then used to estimate connectivity among the distinct occurrence localities of N. lasiopterus, as well as from these latter towards European old-growth forests, under current conditions and different combinations of future timeframes (2030, 2050, 2070) and shared socioeconomic pathways (SSPs 3.70 and 5.85). Results: Current weighted suitability is highest in Andalusia, northern Iberia, southwestern France, peninsular Italy, coastal Balkans and Anatolia, with dispersed suitable patches elsewhere. A north-eastward shift of weighted suitability emerges in the considered future scenarios, especially under SSP 5.85. The major current ecological corridors for N. lasiopterus are predicted within a 'belt' connecting northern Spain and southwestern France, as well as in the Italian Alps. However, following changes in weighted suitability, connectivity would increase in central-eastern Europe in the future. The bioclimatic niche of the western N. lasiopterus populations does not overlap with those of the central and eastern ones, and it only overlaps with climatic conditions characterizing old-growth forests in western Europe. Conclusions: The outcomes of our analyses would help in designing specific conservation measures for the distinct groups of giant noctule populations, favoring the possibility of range expansion and movement towards forested habitats. [ABSTRACT FROM AUTHOR]

A campaign is underway to clear established forests and expand early-successional habitats—also called young forest, pre-forest, early seral, or open habitats—with the intention of benefitting specific species. Coordinated by federal and state wildlife agencies, and funded with public money, public land managers work closely with hunting and forestry interests, conservation organizations, land trusts, and private landowners toward this goal. While forest-clearing has become a major focus in the Northeast and Upper Great Lakes regions of the U.S., far less attention is given to protecting and recovering old-forest ecosystems, the dominant land cover in these regions before European settlement. Herein we provide a discussion of early-successional habitat programs and policies in terms of their origins, in the context of historical baselines, with respect to species’ ranges and abundance, and as they relate to carbon accumulation and ecosystem integrity. Taken together, and in the face of urgent global crises in climate, biodiversity, and human health, we conclude that public land forest and wildlife management programs must be reevaluated to balance the prioritization and funding of early-successional habitat with strong and lasting protection for old-growth and mature forests, and, going forward, must ensure far more robust, unbiased, and ongoing monitoring and evaluation.

Background Suitable climate and availability of habitats for roosting, foraging, and dispersing are critical for the long-term persistence of bat species. The giant noctule (Nyctalus lasiopterus) represents one of the lesser-known European bats, especially regarding the environmental factors which shape its distribution. Methodology We integrated climate-based ecological niche models with information about topography and rivers’ network to model weighted suitability for N. lasiopterus in the western Palearctic. The weighted suitability map was then used to estimate connectivity among the distinct occurrence localities of N. lasiopterus, as well as from these latter towards European old-growth forests, under current conditions and different combinations of future timeframes (2030, 2050, 2070) and shared socioeconomic pathways (SSPs 3.70 and 5.85). Results Current weighted suitability is highest in Andalusia, northern Iberia, southwestern France, peninsular Italy, coastal Balkans and Anatolia, with dispersed suitable patches elsewhere. A north-eastward shift of weighted suitability emerges in the considered future scenarios, especially under SSP 5.85. The major current ecological corridors for N. lasiopterus are predicted within a ‘belt’ connecting northern Spain and southwestern France, as well as in the Italian Alps. However, following changes in weighted suitability, connectivity would increase in central-eastern Europe in the future. The bioclimatic niche of the western N. lasiopterus populations does not overlap with those of the central and eastern ones, and it only overlaps with climatic conditions characterizing old-growth forests in western Europe. Conclusions The outcomes of our analyses would help in designing specific conservation measures for the distinct groups of giant noctule populations, favoring the possibility of range expansion and movement towards forested habitats.

Abstract Background Old-growth forests are irreplaceable with respect to climate change mitigation and have considerable carbon (C) sink potential in soils. However, the relationship between the soil organic carbon (SOC) turnover rate and forest development is poorly understood, which hinders our ability to assess the C sequestration capacity of soil in old-growth forests. Methods In this study, we evaluated the SOC turnover rate by calculating the isotopic enrichment factor β (defined as the slope of the regression between 13C natural abundance and log-transformed C concentrations) along 0–30 cm soil profiles in three successional forests in subtropical China. A lower β (steeper slope) is associated with a higher turnover rate. The three forests were a 60-year-old P. massoniana forest (PF), a 100-year-old coniferous and broadleaved mixed forest (MF), and a 400-year-old monsoon evergreen broadleaved forest (BF). We also analyzed the soil physicochemical properties in these forests to examine the dynamics of SOC turnover during forest succession and the main regulators. Results The β value for the upper 30-cm soils in the BF was significantly (p

Forest disturbances influence Fitzroya cupressoides forest structure and carbon stocks at multiple spatial and temporal scales. Natural disturbances such as landslides and volcanism affect and give rise to the mostly pristine Fitzroya stands present in the Andean cordillera. On the other hand, mostly human-caused fires and logging have been the main processes shaping the structure of Fitzroya stands in the Coastal range and of Fitzroya small remnants in the Central depression. The main goal of this study was to assess the carbon stocks and accumulation rates of Fitzroya forest stands according to their development stage under different disturbance regimes and environmental conditions given by the three physiographic units where the species grows (Coastal range, Central depression, and Andean range). The site selection included an age sequence of stands, known as a chronosequence approach. We identified Fitzroya post-disturbance stands in three different stages of development: young forest stage (mean stand age of the main cohort ≤ 200 years old), mature forest stage (200–800 years old), and old growth forest stage (800–1,500 years old). The following biomass components were considered: living standing trees, dead standing trees (snags), and logs from dead trees laying on the ground (coarse woody debris). Old-growth Fitzroya forests reached a mean total carbon stock (standing live trees, snags, and coarse woody debris) of 507, 279, and 331 Mg C ha−1 in the Andean and Coastal ranges, and Central depression, respectively. Fitzroya cupressoides contributes, in average, more than 80% to the total carbon stock in the Andean and Coastal ranges, and 63% in the Central depression. The remainder corresponds mainly to Nothofagus spp. The high carbon stocks in old-growth stands in the Andean range are explained by Fitzroya longevity, larger size, wood decay resistance, and the low recurrence of volcanic events. Carbon accumulation rates differ between the forests in the three physiographic units (Central depression>Andean range>Coastal range), mainly due to the different growth rates and environmental conditions present in each unit. In the context of climate change, conserving old-growth stands with large biomass and carbon stocks and restoring Fitzroya forests should be recognized as a key contribution toward national and global goals to mitigate global warming.

We assess how the age of Pinus sylvestris mother trees influences seed size, seed viability, germination capacity and later offspring seedling survival under greenhouse conditions. Thirty trees ranging from 30 to 219 years old were selected in the north facing slopes in the Sierra de Guadarrama, where we could find the oldest Pinus sylvestris trees in central Spain. Forty cones per tree were harvested to study cone and seed characteristics (size and weight), seed viability and germination capacity related to the mother tree age. In addition, 25 germinated seeds per tree were grown in a greenhouse to assess offspring seedling survival during a death trial, where watering was stopped. Significant differences between trees in cone and seed morphological traits were observed. The age of the mother tree had a significant effect on cone size, seed size, and seed weight, but there was no effect on seed germination capacity and seed viability. Seedling survival was mainly affected by the decrease in water availability. However, a significant effect of the tree age was found once soil moisture had reached 0%. Our results show the ability of overmature Pinus sylvestris trees to maintain a relatively high reproductive capacity that assures its persistence. [ABSTRACT FROM AUTHOR]

Tree-related microhabitats (hereafter TreMs) are structures occurring on trees, such as rot holes, cavities, large nests, mould, fruiting bodies and mycelia of decomposer fungi. TreMs have been widely recognized as important substrates and structures useful for biodiversity conservation in forest ecosystems, and they can be used as indicators for describing and monitoring forest naturalness. However, most studies on the occurrence of TreMs have been mainly done in forest ecosystems of Central Europe, while less research has been conducted in Mediterranean mountain forests. In this study, we investigated the diversity and abundance of 23 types of TreMs on living trees and on deadwood in seven Mediterranean mountains unmanaged forests located in the Apennines (Italy). The abundance of TreMs was evaluated by counting the number of TreMs per tree, while the diversity of TreMs was evaluated by means of the Shannon-Wiener index. We focused on the relationships between diversity and abundance of TreMs, and tree size (e.g., diameter, height, volume), and the time since the last harvest. Among the investigated stands, 2612 living trees, 457 standing dead trees and snags, and 1247 lying deadwood pieces were analysed. For living trees, a generalized linear mixed model was applied to test the effect of several variables on the abundance of TreMs per tree. Diameter at breast height (DBH) of tree stems influenced the abundance and diversity of TreMs. The time since the last harvest also significantly affected the probability that TreMs could be formed in a long-term perspective. The interaction of the predictors “DBH2” and “Years since the last harvest” generated a better model than the one in which the two variables were kept separate. Indeed, these two factors together would better represent the transition of a previously managed forest to a more natural state over time. This study might provide useful information to land managers committed to forestry practices towards sustainable management and biodiversity conservation, especially referring to survey and inventory of forests of high nature value.

Old-growth forests are considered a benchmark for naturalness and models to which one compares managed forests, comparison leading to debates around biodiversity and its conservation, structure and dynamics, polarizing conservationists and forest practitioners. Plant pathogens are frequently disregarded as components of forests biodiversity, the common perception referring to this category of organisms as important biotic stressors. However, pathogens building several functional groups (necrotrophic and biotrophic pathogens, endophytic pathogens, sapro-parasitic species, generally on wood), in highly natural forests such as old-growth forests are establishing interaction networks with several other functional groups of organisms such as hyperparasites, consumers, disease facilitators, indirect opportunistic species (such as tree hollow dwellers), saprotrophs or mutualists. Being connected to old trees (rare or missing components of managed forests) or to endangered forest plants, pathogens become indicators of naturalness and biodiversity. The gradient going from saprotrophs, to sapro-pathogens and generalist/specialist pathogens characterizing forest ecosystems is linked at great extent to wood and bark, being connected to nutrient cycling as ecosystem level process. As long as disease is maintained within the baseline mortality of the trees, pathogens play the important role of control factors and contribute directly and indirectly to forest biodiversity. The current disease ecology progresses, the biodiversity integrative studies, and the new holistic approaches shaping modern ecology bring in the focus rare, endemic pathogens as important control factors of plant populations, as components of the plants’ phenotypic niche and of the global biodiversity, as potential providers of services (sources of medicines) and components of the intricate ecological webs. However, the comparisons between old-growth and managed forests biodiversity should be focused on species evenness (high evenness in old-growth forests versus low evenness in managed forests) and not particularly on species richness. Still, there are pathogens responsible for major biotic disturbances in forests worldwide, the invasive, alien or emerging pathogens threatening both old-growth forests and managed forests.

Old-growth forests have an important role in maintaining animal and plant diversity, are important carbon (C) reservoirs and are privileged sites to study long-term plant physiological responses, long-term forest dynamics and climate change impact on forest ecosystems. Several studies have highlighted how old-living trees undergo age-related declines with hydraulic limitations and reduction in photosynthesis, though some recent works have suggested that such a decline is not always observed. Our study aims at understanding the role of atmospheric CO2 increase on tree C uptake and stomatal conductance (gs) in old-living trees by analysing the long-term patterns of tree growth and intrinsic water use efficiency (iWUE) in three old-growth forests in the Balkans (Bosnia-Herzegovina and Montenegro), using dendrochronology and isotopic analysis. We hypothesised a long-term increase in iWUE in the studied old-growth forests, mostly related to enhanced photosynthesis rather than reduced stomatal conductance. Tree cores were sampled from dominant silver fir (Abies alba Mill.) trees in each forest. Tree-ring widths were measured and basal area increments (BAI) were assessed for each sampled tree and, from the six longest chronologies, five decades were chosen for cellulose extraction, its isotopic analysis (δ13C, δ18O), iWUE and leaf water 18O evaporative enrichment above the source water (Δ18OL) determination. We observed a continuous and significant increase in iWUE from 1800 to 2010 in the sampled dominant trees at all the three old-growth forests. Our BAI data and our estimates of Δ18OL across the study period support the idea that enhanced photosynthesis rather than reduced stomatal conductance is the major driver of the measured iWUE increase. Thus, our results support some recent findings challenging the hypothesis that iWUE in forests is primarily the result of a CO2-induced reduction in stomatal conductance as well as the so called hydraulic limitation hypothesis.

This article tracks changing conceptions of time in European forest science over recent decades, and accounts for how they can affect forest conservation and management. Through semiotic analysis of 62 peer-reviewed articles published in ecology and forestry, we (1) characterize the temporal features of old European forests as they evolve over our study period (1997–2017), and (2) trace how new and changing temporalities in forest science have reconfigured what constitutes a problem for conservationists and managers. We describe in particular how two articulations of forest time and forest management—Forest Continuity and Forest Maturity—have evolved, identifying the emergence of two new temporalities in old forest science. Over the study period, changing conceptions of forest pasts have increasingly led to consider forests as complex and evolving ecosystems from which humans cannot be excluded. • Forest temporalities are an important research problem in European forest science. • Two new forest temporalities have appeared: extinction debt and long-term history. • Changing conceptions of forest pasts affect old forest conservation practice. • Forest pasts are performative because they are constitutive of "old forests". [ABSTRACT FROM AUTHOR]

Old forests containing ancient trees are essential ecosystems for life on earth. Mechanisms that happen both deep in the root systems and in the highest canopies ensure the viability of our planet. Old forests fix large quantities of atmospheric CO2, produce oxygen, create micro-climates and irreplaceable habitats, in sharp contrast to young forests and monoculture forests. The current intense logging activities induce rapid, adverse effects on our ecosystems and climate. Here we review large old trees with a focus on ecosystem preservation, climate issues, and therapeutic potential. We found that old forests continue to sequester carbon and fix nitrogen. Old trees control below-ground conditions that are essential for tree regeneration. Old forests create micro-climates that slow global warming and are irreplaceable habitats for many endangered species. Old trees produce phytochemicals with many biomedical properties. Old trees also host particular fungi with untapped medicinal potential, including the Agarikon, Fomitopsis officinalis, which is currently being tested against the coronavirus disease 2019 (COVID-19). Large old trees are an important part of our combined cultural heritage, providing people with aesthetic, symbolic, religious, and historical cues. Bringing their numerous environmental, oceanic, ecological, therapeutic, and socio-cultural benefits to the fore, and learning to appreciate old trees in a holistic manner could contribute to halting the worldwide decline of old-growth forests. [ABSTRACT FROM AUTHOR]

The Interior Wetbelt (IWB) of British Columbia includes the globally rare Inland Temperate Rainforest (ITR) that if managed for its substantial carbon (C) stocks can contribute to Canada's Nationally Determined Commitment under the Paris Climate Agreement. We provide spatially explicit estimates of above‐ and belowground live and dead biomass and soil C stocks derived from three sources: (1) government online Vegetation Resources Inventory (VRI); (2) the GlobBiomass spatial dataset; and (3) field plots (n = 27) within old‐growth forests of the ITR. For live aboveground C, we summarize C stocks by elevation classes and decadal forest age. The upper bound on total C densities (above‐ and belowground live and dead biomass and soil C) based on VRI was a maximum of 806 megagrams (Mg) C ha−1. The mean total biomass C density measured in field plots was 583 Mg C ha−1 with a maximum of 1275 Mg C ha−1, which is on par with some of the world's most C‐dense temperate forests. About half the C is in live biomass pools with the rest in dead biomass and soil organic C pools. The mean C density from the VRI over all elevations was 182 Mg C ha−1, with soil organic C ~40% and live tree stems ~27%. Vegetation Resources Inventory estimates were 75% lower than field‐based measurements with the greatest mismatch in areas with the highest C density. Approximately 22% of the IWB has been logged, the majority since 1970s, resulting in live above ground C declining by at least 18%, although this is likely an underestimate. Logging was heavily concentrated in low (<1000 m; 28.3% of elevation zone) to mid‐elevations (1000–2000 m; 20.9%) compared with upper elevations (>2000 m; 1.2%). The region contains underappreciated C stocks that can help Canada meet its climate and conservation targets, but only if there are major forestry reforms that protect C‐dense old‐growth forests, allow degraded forests time to recover the logging‐related C debt, and improve monitoring of C stocks and stock changes. [ABSTRACT FROM AUTHOR]

Snow duration in post‐fire forests is influenced by neighbourhoods of trees, snags, and deadwood. We used annually resolved, spatially explicit tree and tree mortality data collected in an old‐growth, mixed‐conifer forest in the Sierra Nevada, California, that burned at low to moderate severity to calculate 10 tree neighbourhood metrics for neighbourhoods up to 40 m from snow depth and snow disappearance sampling points. We developed two linear mixed models, predicting snow disappearance timing as a function of tree neighbourhood, litter density, and simulated incoming solar radiation, and two multiple regression models explaining variation in snow depth as a function of tree neighbourhood. Higher densities of post‐fire large‐diameter snags within 10 m of a sampling point were related to higher snow depth (indicating reduced snow interception). Higher densities of large‐diameter trees within 5 m and larger amounts of litter were associated with shorter snow duration (indicating increased longwave radiation emittance and accelerated snow albedo decay). However, live trees with diameters >60 cm within 10 m of a snow disappearance sampling point were associated with a longer‐lasting spring snowpack. This suggests that, despite the local effects of canopy interception and emitted longwave radiation from boles of large trees, shading from their canopies may prolong snow duration over a larger area. Therefore, conservation of widely spaced, large‐diameter trees is important in old‐growth forests because they are resistant to fire and can enhance the seasonal duration of snowmelt. [ABSTRACT FROM AUTHOR]

Abstract Invasion by generalist tree species can cause biotic homogenization, and such community impoverishment is likely more important in rare forest types. We quantified changes in tree diversity within Carolinian (range in Central Hardwood Forest), central (range in Central Hardwood Forest and Northern Hardwood‐Conifer Forest), and northern species [range reached Northern‐Conifer‐Hardwood/closed Boreal (spruce‐Fir) Forest] in an old forest tract in southern Canada at points surveyed 24 years apart. We asked: How did mature tree and sapling composition and abundance change for the three species’ groups? Did those changes lead to biotic homogenization? Can species’ changes be explained by community traits? We tested for differences in temporal and spatial tree β‐diversity, as well as forest composition and structure, using univariate/multivariate analyses and a community trait‐based approach to identify drivers of change. Major increases occurred in abundance for mature Acer rubrum (northern), while other species decreased (Fraxinus americana, Populus grandidentata); declines were found in A. saccharinum (central) and Cornus florida (Carolinian). Species composition of saplings, but not mature trees, changed due to replacement; no evidence for biotic homogenization existed in either cohort. As a group, northern mature tree species increased significantly, while central species decreased; saplings of pooled Carolinian species also declined. Shade tolerance in mature trees increased, reflecting successional changes, while drought tolerance decreased, perhaps due to changing temperatures, altered precipitation or ground water levels. Saplings showed declines in all traits, probably because of compositional change. Our results demonstrated that saplings can more closely reflect change in forest dynamics than mature trees, especially over short time periods. Based on sapling trends, this remnant could ultimately transition to a mesophytic hardwood stand dominated by A. rubrum and other shade‐tolerant species, creating a more homogeneous forest. While encouraging regeneration for Carolinian and central tree species could ensure high levels of diversity are conserved in the future, it is important to balance this with the primary management goal of maintaining the forest's old‐growth characteristics.

The main goal of this paper was to evaluate structure dynamics in the fir-beech, old-growth forest Badínsky prales. Measurements were taken on four permanent research plots (0.5 ha each) between 1970 and 2018, typically in ten-year intervals. In order to assess long-term structure dynamics, this study used basic stand characteristics and selected structural indices - the relative density (RD), coefficient of homogeneity (H), and structural complexity index (SCI). Species composition was quantified by the relative importance value (RIV), and a detrended correspondence analysis was carried out for the visualisation of long-term changes. The long-term mean of the stand volume reached 634 ± 99 m3.ha-1, and the mean of the basal area was 36.6 ± 4.0 m2.ha-1. Calculated values of the coefficient of homogeneity (1.46-2.54) were similar to values in other old-growth forests with a comparable tree species composition. An increasing trend in beech RIV values was observed; on the other hand, fir RIV values fell by approximately 20%-25%. In 2018, maximal values of the basal area, stand volume and relative density were recorded. These high values may indicate better growth conditions due to climate change, as well as fewer disturbance events in the last few decades.

Abstract The Interior Wetbelt (IWB) of British Columbia includes the globally rare Inland Temperate Rainforest (ITR) that if managed for its substantial carbon (C) stocks can contribute to Canada's Nationally Determined Commitment under the Paris Climate Agreement. We provide spatially explicit estimates of above‐ and belowground live and dead biomass and soil C stocks derived from three sources: (1) government online Vegetation Resources Inventory (VRI); (2) the GlobBiomass spatial dataset; and (3) field plots (n = 27) within old‐growth forests of the ITR. For live aboveground C, we summarize C stocks by elevation classes and decadal forest age. The upper bound on total C densities (above‐ and belowground live and dead biomass and soil C) based on VRI was a maximum of 806 megagrams (Mg) C ha−1. The mean total biomass C density measured in field plots was 583 Mg C ha−1 with a maximum of 1275 Mg C ha−1, which is on par with some of the world's most C‐dense temperate forests. About half the C is in live biomass pools with the rest in dead biomass and soil organic C pools. The mean C density from the VRI over all elevations was 182 Mg C ha−1, with soil organic C ~40% and live tree stems ~27%. Vegetation Resources Inventory estimates were 75% lower than field‐based measurements with the greatest mismatch in areas with the highest C density. Approximately 22% of the IWB has been logged, the majority since 1970s, resulting in live above ground C declining by at least 18%, although this is likely an underestimate. Logging was heavily concentrated in low (2000 m; 1.2%). The region contains underappreciated C stocks that can help Canada meet its climate and conservation targets, but only if there are major forestry reforms that protect C‐dense old‐growth forests, allow degraded forests time to recover the logging‐related C debt, and improve monitoring of C stocks and stock changes.

Records of Cyphella digitalis from the Czech Republic and Slovakia are summarised and discussed. ITS barcode of two collections was obtained to document their conspecificity with the only so far sequenced sample originating from the Alps. In the study area, C. digitalis is rare with ten localities known from the 20th century and nine recorded in the 21st century. They are situated in the Bohemian Forest and several mountain ranges of the Western and Eastern Carpathians. The elevation range of the records is 525--1200 m a.s.l. All records are from Abies alba, mostly branches attached to freshly fallen trunks and sticking out into the air. Basidiomata occur in Fagus-Abies or Fagus-Abies- Picea forests from September to March with a peak in September--November. Most stands represent old-growth forests under protection. Ecology and distribution are discussed in a broad European context. The much lower number of records in the Czech Republic and Slovakia compared to more western countries could have, among other things, also biogeographical reasons, i.e. decrease in occurrence with increasing continentality to the east. [ABSTRACT FROM AUTHOR]

Old-growth forests are considered a benchmark for naturalness and models to which one compares managed forests. The comparison led to debates around biodiversity and its conservation, structure and dynamics, polarizing conservationists and forest practitioners. Plant pathogens are frequently disregarded as components of forests biodiversity, the common perception referring to this category of organisms as important biotic stressors. However, pathogens are building several functional groups such as necrotrophic and biotrophic pathogens, endophytic pathogens, sapro-parasitic species, in highly natural forests including old-growth forests. They are establishing interaction networks with several other functional groups of organisms such as hyperparasites, consumers, disease facilitators, indirect opportunistic species (such as tree hollow dwellers), saprotrophs or mutualists. Being connected to old trees (rare or missing components of managed forests) or to endangered forest plants, pathogens become indicators of naturalness and biodiversity. The gradient going from saprotrophs, to sapro-pathogens and generalist/specialist pathogens characterizing forest ecosystems is linked at great extent to wood and bark, being connected to nutrient cycling as ecosystem level process. As long as disease is maintained within the baseline mortality of the trees, pathogens play the important role of control factors and contribute directly and indirectly to forest biodiversity. The current disease ecology progresses, the biodiversity integrative studies, and the new holistic approaches shaping modern ecology bring in the focus rare, endemic pathogens. These play several roles: as important control factors for plant populations, as components of the plants’ phenotypic niche and of the global biodiversity, as potential providers of services (sources of medicines) and as components of the intricate ecological webs. However, the comparisons between oldgrowth and managed forests biodiversity should be focused on species evenness (high evenness in old-growth forests versus low evenness in managed forests) and not particularly on species richness. Still, there are pathogens responsible for major biotic disturbances in forests worldwide, the invasive, alien or emerging pathogens threatening both old-growth forests and managed forests. [ABSTRACT FROM AUTHOR]

Background: Old-growth forests are irreplaceable with respect to climate change mitigation and have considerable carbon (C) sink potential in soils. However, the relationship between the soil organic carbon (SOC) turnover rate and forest development is poorly understood, which hinders our ability to assess the C sequestration capacity of soil in old-growth forests. Methods: In this study, we evaluated the SOC turnover rate by calculating the isotopic enrichment factor β (defined as the slope of the regression between 13C natural abundance and log-transformed C concentrations) along 0–30 cm soil profiles in three successional forests in subtropical China. A lower β (steeper slope) is associated with a higher turnover rate. The three forests were a 60-year-old P. massoniana forest (PF), a 100-year-old coniferous and broadleaved mixed forest (MF), and a 400-year-old monsoon evergreen broadleaved forest (BF). We also analyzed the soil physicochemical properties in these forests to examine the dynamics of SOC turnover during forest succession and the main regulators. Results: The β value for the upper 30-cm soils in the BF was significantly (p < 0.05) higher than that in the PF, in addition to the SOC stock, although there were nonsignificant differences between the BF and MF. The β value was significantly (p < 0.05) positively correlated with the soil recalcitrance index, total nitrogen, and available nitrogen contents but was significantly (p < 0.01) negatively correlated with soil pH. Conclusions: Our results demonstrate that SOC has lower turnover rates in old-growth forests, accompanied by higher soil chemical recalcitrance, nitrogen status, and lower soil pH. This finding helps to elucidate the mechanism underlying C sequestration in old-growth forest soils, and emphasizes the important value of old-growth forests among global C sinks. [ABSTRACT FROM AUTHOR]

The relationships between structural complexity, deadwood abundance, microhabitat type and species-diversity indicators are excellent tools to monitor biodiversity in forest ecosystems.In spite of their importance, correlations between structural traits and Coleoptera communities in Mediterranean mountain forests have only rarely been investigated. Consequently, the magnitude and direction of the relationships between forest traits and biodiversity indicators remain poorly understood. In this study, we analyzed whether biodiversity indices of saproxylic and non-saproxylic beetle communities could be influenced by stand structure, microhabitat type, and deadwood abundance in two protected beech forests located in the central and southern Apennines (namely Gran Sasso e Monti della Laga National Park, GSML, and Cilento, Vallo di Diano e Alburni National Park, CVDA). Standard measurements of forest structural traits and quantitative assessment of tree microhabitats and deadwood were carried out. Adult beetles were collected using window flight traps and emergence traps on decaying deadwood. The two beech forests were different in terms of both beetle communities and structural traits. A two-block partial least squares analysis 2B-PLS highlighted differences in biodiversity indices and structural traits between the two forest ecosystems. In GSML, we observed that biodiversity indices were positively correlated with the volume of coarse woody debris and the presence fungal infections, clefts into the sapwood, and woodpecker cavities, while more dominant beetle communities were found under denser canopy cover. In CVDA, Coleoptera abundance was positively correlated with the basal area and crown broken microhabitats. Our results point toward the relevance of ecological attributes in tracking changes in beetle biodiversity in specific forest contexts. In these protected Mediterranean mountain beech stands, in which the main forest management strategies have the primary objective of biodiversity conservation, we suggest to progressively increase the structural diversity and canopy dynamics, as well as the volume of coarse woody debris.

With 62 % of its total area covered in forest, Styria is the most densely forested province in Austria. Accordingly, forests, more than any other habitat, characterise the landscape in the Styrian Eisenwurzen Nature and Geopark. The forest areas of the nature park are managed by a combination of private owners and the Styrian Provincial Forests, the Austrian Federal Forests and the City of Vienna. The near-natural areas of the nature park forests in particular are characterised by species-rich fauna and flora, which include specially protected species. However, the forests of the nature park do not simply provide habitats for a large number of protected animal and plant species. Due to their location - embedded between the Dürrenstein wilderness area, the Kalkalpen National Park and the Gesäuse National Park - they also function as important stepping-stone habitats for many forest-bound species. [ABSTRACT FROM AUTHOR]

Dendrochronological analyses were conducted across a gradient of productivity and soil drainage quality characterizing four vegetation types in a low‐productivity hypermaritime (perhumid) temperate rainforest on the Central Coast of British Columbia, Canada. We examined the structure, composition, and stand dynamics of trees growing in 400 m2 plots located in blanket bog, bog woodland, bog forest, and zonal forest vegetation types. We sampled over 2500 trees and 1500 seedlings and saplings and our dendrochronological reconstruction of six tree species revealed establishment ages extending to 660 A.D. (1350 yr). All forest plots contained numerous old trees (>250 yr) and the zonal forest and bog forest vegetation types contained significantly taller trees and also had the greatest amount of suppressed, shade‐tolerant tree species. The bog woodland vegetation type contained more seedlings and saplings than the other three vegetation types combined. The bog forest vegetation type had the highest density of dead standing trees (~530 per hectare). Blanket bogs contained an open structure with very few old trees (>250 yr). Significant differences in the ages of trees existed between forested vegetation types and the more open blanket bog vegetation type. Several trees exceeded 1000 yr in age and were situated in lower‐productivity bog forest and bog woodland sites. We found no evidence of widespread tree cohort establishment, indicating that small‐scale disturbances such as individual tree mortality and gap‐forming dynamics are likely the most frequent disturbance in the study area. [ABSTRACT FROM AUTHOR]

The Decree on Climate 2019 represents an innovative and concrete framework for applying the international recommendations aimed at preventing and mitigating the effects of climate change. It focuses, in addition to many environment-related aspects, on the old-growth forests, recognizing them as forest ecosystems of high environmental value, defining their main ecological traits. According to this legislation, the extent of these forests in Italy is important, since many forest ecosystems have been left unmanaged from more than 60 years. Even if these stands are not always characterized by high level of naturalness, they are currently evolving towards more complex structures, due to the absence of human-related disturbance. Old-growth forests are unique ecosystems with a high structural complexity and peculiarities that are absent in managed forests. They are also an essential point of reference for sustainable forest management and environmental monitoring, in terms of conservation of biological diversity and ecological processes. For these reasons, they represent a unique benchmark for developing silvicultural models that incorporate knowledge of structural complexity (vertical and spatial) and developmental processes, duration of development and particularly the role of disturbances in creating structural legacies that become key elements of the post-disturbance stands. These forests, as the new Decrete underlines, must be protected, preserved and monitored in a long-term perspective, in order to safeguard their biodiversity, avoiding the structural simplification, which often characterizes the managed forests.